Regular exercise can do more than just strengthen the body. New research findings from Victoria University (VU) support the idea that physical activity may also play an important role in the health of the aging brain. This includes processes associated with age-related cognitive decline and, possibly, with conditions such as dementia and Alzheimer’s disease.
How Exercise Can Support the Aging Brain
VU researcher Dr. James Broatch led an analysis examining how exercise might influence the so-called glymphatic system. Put simply, this is a drainage system in the brain that, among other things, helps remove certain metabolic byproducts from brain tissue. This system is particularly active during sleep.
Research into the importance of the glymphatic system for brain health is growing. At the same time, it is already well established that regular physical activity has numerous positive effects on health and healthy aging. However, the exact mechanisms involved are not yet fully understood. Research into these connections is also of interest because more than 10 million people worldwide are newly diagnosed with dementia each year. There is currently no cure.
The peer-reviewed review article was recently published in the journal *Trends in Neurosciences *. To this end, the researchers analyzed existing studies on the glymphatic system in animals and humans. Their findings showed that physical activity can influence several physiological processes that may be related to the function of the glymphatic system. These include, among other things, a reduction in blood pressure and vascular stiffness, changes in neuronal activity, a reduction in inflammatory processes, and potential improvements in sleep.
Sleep and the Brain’s “Cleanup System”
Sleep is particularly important because the glymphatic system is especially active during sleep. It helps remove metabolic waste products from the brain. However, as we age, both sleep and various brain functions change—which raises the interesting question of whether exercise can support these processes. Dr. Broatch and his team therefore investigated what effects physical activity might have on the various processes related to the function of the glymphatic system. The analysis suggests that exercise could play a role in this through several mechanisms.
These include, among other things, improved vascular health, reduced inflammation, and more restful sleep. At the same time, there is evidence that exercise can improve sleep quality and, in particular, promote deep sleep. So-called slow-wave activity during certain sleep phases is also linked to the brain’s cleansing processes. Thus, exercise could potentially improve the conditions under which the glymphatic system operates during sleep. The researchers see this as an interesting starting point for further dementia research. However, this is currently only a potential biological mechanism. Current research does not prove that more exercise automatically leads to better glymphatic function, nor that it can prevent dementia. Further studies are needed to determine which type of exercise, duration, and intensity are particularly beneficial for this relationship.
The Importance of Exercise for Brain Health
Beyond the glymphatic system, there is ample evidence that exercise is important for brain health: Physical activity is associated with a lower risk of cognitive decline and dementia. It is unlikely that a single mechanism is responsible for this. Rather, various positive effects on the body and the brain combine.
Regular physical activity can, among other things, improve cardiovascular health and help lower blood pressure and blood sugar levels. Blood flow to the brain can also benefit from this. Good vascular health, in turn, is important because changes and diseases of the blood vessels are among the factors that can contribute to cognitive impairment. Furthermore, exercise can influence metabolism and is associated with reduced chronic inflammation. Mental health can also benefit: Physical activity is associated with, among other things, improved mood and a lower risk of depressive symptoms. Last but not least, exercise plays a role in sleep, which in turn is important for the brain’s recovery and performance.
Researchers are therefore increasingly seeking to understand the various ways in which physical activity can influence the brain over the long term. The findings from Victoria University thus add an interesting new perspective to the already established links between exercise and brain health: the function of the glymphatic system. However, they do not provide evidence that exercise prevents Alzheimer’s or other forms of dementia. Rather, they highlight potential biological links that need to be investigated in further studies.
Strength Training Could also Help With Healthy Aging
When it comes to brain health, strength training is also increasingly becoming a focus of research. Another large observational study provides evidence that regular strength training may be associated with a lower risk of premature death.
For the study, researchers analyzed data from three long-term U.S. studies involving a total of nearly 150,000 nurses and other healthcare professionals. The participants were followed for up to 30 years and provided information at regular intervals about their physical activities, including strength training and endurance exercises such as walking, cycling, or swimming.
During the follow-up period, nearly 36,000 participants died. This revealed a particularly interesting association: people who reported doing about 90 to 120 minutes of strength training per week had a roughly 13 percent lower risk of dying than those who did not engage in strength training. The association was even more pronounced for certain causes of death. The risk of dying from cardiovascular disease was about 19 percent lower among those who did strength training. For deaths due to neurological diseases—primarily dementia—the difference was around 27 percent.
However, in this study, more strength training did not automatically lead to additional benefits. Beyond about two hours per week, there was no further reduction in the risk of death. The combination of strength and endurance training was particularly beneficial. Even the recommended amount of moderate-intensity endurance activity —about 150 minutes per week—was associated with a significantly lower risk of death. When this activity was combined with one to two hours of strength training per week, the association with the lowest mortality rate was particularly pronounced.
Why Muscles Are Also Important for Health
The potential benefits of strength training extend far beyond muscle building and physical performance. Skeletal muscle plays an important role in metabolism. After a meal, muscles absorb a large portion of the glucose present in the blood and can use it for energy or store it as glycogen. Regular strength training can therefore help improve insulin sensitivity and blood sugar regulation. Well-trained muscles can thus be particularly important in the context of obesity and type 2 diabetes.
In addition, muscles release substances known as myokines during activity. These are signaling molecules that allow the muscles to communicate with other organs. Research is increasingly examining the role these signaling molecules play in metabolism, inflammatory processes, and brain health, among other things. Strength training can also have benefits for the cardiovascular system. Regular physical activity can, among other things, help regulate blood pressure and support vascular health.
Strength Training and the Brain
The link between strength training and brain health has not yet been studied as extensively as the general link between physical activity and healthy aging. However, initial research findings are intriguing.
One possible explanation is that strength training influences several factors that are also important for the brain. These include, for example, blood sugar, blood pressure, vascular health, and inflammatory processes. If these factors are positively influenced over the long term, this could also benefit the brain.
Accordingly, the large observational study found an association between strength training and a lower risk of dying from neurological diseases. However, it cannot be concluded from this that strength training prevents dementia. The study shows a statistical association and cannot prove that the training itself is responsible for the lower mortality rate.
Other differences among the participants may also have played a role. Although the researchers took various influencing factors into account—such as diet, smoking, and other physical activities—possible biases always remain in an observational study.
How Much Strength Training is Beneficial?
The results do not suggest that you need to train for hours every day. On the contrary: In the study, the range associated with the most beneficial effect was about 90 to 120 minutes of strength training per week.
For overall health, it can therefore be beneficial to regularly incorporate strength training into your daily routine while also getting enough endurance exercise. This doesn’t necessarily have to be a traditional gym workout. Exercises using your own body weight, resistance bands, or other simple forms of exercise can also work your muscles. The key is, above all, to be active regularly and to engage as many large muscle groups as possible.
These findings thus complement research on the link between exercise and brain health: endurance training and strength training do not have to be mutually exclusive. Rather, a combination of different forms of exercise could be particularly beneficial for healthy aging.
Researchers Are Still Searching for the Optimal Form of Exercise
It is not yet clear how much exercise is particularly beneficial for glymphatic function or which type of exercise might have the greatest effect. The researchers therefore aim, among other things, to determine whether certain forms of exercise are more suitable than others and whether recommendations should differ for people with existing cognitive decline or a diagnosed neurological disorder. The question of how often and how intensely one should exercise has also not yet been conclusively answered.
Despite these unanswered questions, there is strong evidence in favor of making exercise a regular part of daily life. This is because physical activity not only affects muscles and the cardiovascular system but can also positively influence sleep, metabolism, vascular health, and possibly various processes in the brain. Dr. Broatch therefore emphasizes that regular exercise—especially activities that increase heart rate—is important for overall health. Developing good exercise habits as early in life as possible could therefore also play an important role in healthy aging. The new research provides another possible piece of the puzzle as to why exercise might be so valuable for our brains as well.